Combined EC pills are about 75 percent effective. Progestin-only EC pills are 89 percent effective if used within 72 hours and 95 percent effective if used within 24 hours.

Why is this such a big deal? The common perception is that EC pills are a magic treatment that WILL prevent the pregnancy from starting. There is no easy way to undo the effects of a violent sex assault. A certain percentage of women will, in fact, become pregnant - about 5%, same as any other single act of unprotected sex. The way I've seen the statistics on effectiveness thrown around makes me quite suspicious of them - too many people will confuse the numbers, say that if 95% of rape victims don't get pregnant, then the treatment was 95% effective.

In fact, in such a case, the treatment had NO effect - about 5% would have become pregnant in any case.

Another concern is - what about the 95% who WOULDN'T have become pregnant? They are being given some very powerful hormones that may have long-term side effects. And, they are being pressured to take that treatment at a VERY vulnerable point in their lives, while they are quite traumatized from the attack.